Chun's "American PT Boats of World War II" includes a copy of the ELCO Adapter Scheme drawing (stbd side only).
Chun states that the adapter scheme was ineffective in the Pacific. The crew quickly painted over the stripes with dark green. "The only area the zebra pattern was used was in the Mediterranean".
So that lets out the zebra as meeting the original poster's South Pacific needs.
Chun also has several zebra photos not generally seen.
The previously cited "Allied Torpedo Boats" by Lambert & Brown shows photos of several different adapter schemes and state that 'no two Adapter patterns were exactly alike'. Further they state that the only users of the black & white version were Higgins boats of Squadron 15 in the Mediterranean.
Once again the Mediterranean lets out the OP's South Pacific needs.
GMorrison: The text which accompanies Shaun Symonds build shown in Lambert & Browns book indicates that he used Gator Mask masks to paint the pattern.
An alternate source of the pattern may come from eCardModels. They offer a 1:48 paper model of an 80' ELCO in zebra. Use some creative Xerography to blow the paper model up to 1:35 -- then cut the stripes and apply as masks. A water-soluable glue stick (grade school item) is good to temporarily attach paper strips as hard-edge masks